67 fuse box question

[tnblazerk5]

this is on a 67 with that came with a 6 banger if it matters
from standing under the hood the lower right red wire in the fuse box lost contact with what ever it is hooked to inside the fuse box and therefor theres is no power to the inside of the cab and had to hot wire it to get it home and i need to know if there is way to temp fix that ?
what does it hook to inside the fuse box ? and where does the other end of the wire come out inside the truck or does it ? and is there a way to bypass the part inside the box ( i have never had the box out and have no clue what all is in there )

i got a differant cab to put on the truck and a new harness and really want to drive my truck while the other cab is getting ready to be tore apart and get sum work done to it and i see no reasion to put a differant harness in the old cab just to drive it for a short while and then take it back out and put it in the redone cab, maybe i am just lazy but thats a lot of extra work to me